The invention relates to concrete pumps, in particular truck mounted concrete pumps, however, it is not limited to conveying concrete but is applicable to conveying thick matters in general, thus sludges of any type.
For above-ground construction and also for underground construction, concrete pumps of various types and various power ratings are being used in order to put out concrete that is delivered on site by mixing vehicles in order to form walls, ceilings and similar. Thus stationary concrete pumps and also mobile concrete pumps, in particular so-called truck mounted concrete pumps are being used. In the case of truck mounted concrete pumps, the pump is arranged on a frame or a bed of a truck and sucks concrete from a filling funnel that is arranged at the vehicle, wherein the concrete is put out in a controlled manner at the construction site through an outgoing feed conduit. Truck mounted concrete pumps of this type typically include a boom which is configured from plural boom arms linked with one another which can be pivoted in, in a space saving manner for driving operations, so that the boom arms of the boom are arranged more or less parallel but are folded together in a tight space on the frame or the bed so that road transportation is easily provided. These booms are supported through a pivot link on a swivel bogie which is supported rotatable about its vertical axis at the vehicle frame, in particular at a boom block that is fixated at the vehicle. Through the swivel bogie with the swivel boom linked thereto in a pivotable manner, the boom is extensible through folding out the boom arms and can be rotated or swiveled by 360° about the rotation axis of the swivel bogie. Thus a very large area can be supplied with concrete once the vehicle is positioned.
Since for a more or less extended boom which can be furthermore swiveled at will about the swivel bogie axis and thus is also adjustable into a position that laterally extends from the vehicle, respective pivot torques can be imparted upon the concrete vehicle. These vehicles are provided with laterally extensible supports in order to provide a safe support of the vehicle that is secured against tipping. However, these supports are quite critical and depending on the length of the boom a support is required that is adapted accordingly. Thus, as a function of the extended position of the boom relative to the vehicle and the center of gravity of the truck mounted concrete pump a respective deployment position of the support elements is required. This is difficult on site since conditions are often provided at construction sites which severely restrict the positions of the support elements so that depending on the construction site or the position of the vehicle, the support elements can be fully deployed on one side and cannot be deployed or can only be partially deployed on the other side. In case that the tilt moments that are caused by the deployed boom cannot be received by the support bases, the vehicle can flip. It is apparent that it can't be left up to the driver of the concrete delivery vehicle on site to determine from which swivel or deployment position of the boom a flipping of the vehicle can occur in order to deploy the support bases accordingly. Therefore, the pumps, in particular the truck mounted concrete pumps are configured with systems which also capture and process the precise position of the swivel ring in addition to the deployment of the boom in order to be able to take appropriate safety precautions at any time.
In a known embodiment, an end switch is used for rotation angle determination which end switch is mounted at an outer circumference of the swivel ring of the swivel bogie. It is disadvantageous for this embodiment that only an end position of the system is detected. Furthermore this system provides no redundancy against failure. In particular, however, this system is not suitable for measuring a plurality of intermediary positions of the swivel ring since this would require a substantial number of end switches. This, however, would cause very high complexity for wiring the components and would cause overall assembly complexity.
In another known system the position of the swivel ring is captured by two rotation angle sensors arranged at an outer circumference, wherein the rotation angle sensors are respectively provided with an individual drive and a transmission connected there between. Though this can reliably measure any position of the swivel ring and thus also provide the required redundancy for the system, however, it requires high manufacturing complexity. Additionally these rotation angle sensors are rather bulky and have relatively high weight which is disadvantageous for a light weight construction of the entire machine. Thus, overall this system is rather expensive.